Free-cutting copper alloy, and method for producing free-cutting copper alloy

A free-cutting copper alloy worked material that is obtained by performing any one or both of cold working and hot working the free-cutting copper alloy worked material comprising:

• 75.5 mass % to 78.0 mass % of Cu;
• 3.1 mass % to 3.4 mass % of Si;
• 0.10 mass % to 0.27 mass % of Sn;
• 0.06 mass % to 0.13 mass % of P;
• 0.024 mass % to 0.24 mass % of Pb;
• and
• a balance including Zn and inevitable impurities,
• wherein a total amount of Fe, Mn, Co, and Cr as the inevitable impurities is lower than 0.08 mass %,
• when a Cu content is represented by [Cu] mass %, a Si content is represented by [Si] mass %, a Sn content is represented by [Sn] mass %, a P content is represented by [P] mass %, and a Pb content is represented by [Pb] mass %, the relations of
• 76.6≤f1=[Cu]+0.8×[Si]−8.5×[Sn]+[P]+0.5×[Pb]≤79.6 and
• 61.7≤f2=[Cu]−4.3×[Si]−0.7×[Sn]−[P]+0.5×[Pb]≤63.2
• are satisfied,
• in constituent phases of metallographic structure, when an area ratio of α phase is represented by (α) %, an area ratio of β phase is represented by (β) %, an area ratio of γ phase is represented by (γ) %, an area ratio of κ phase is represented by (κ) %, and an area ratio of μ phase is represented by (μ) %, the relations of
• 30≤(κ)≤56,
• 0≤(γ)≤0.8,
• (β)=0,
• 0≤(μ)≤1.0,
• 98.0≤f3=(α)+(κ),
• 99.6≤f4=(α)+(κ)+(γ)+(μ),
• 0≤f5=(γ)+(μ)≤1.5, and
• 32≤f6=(κ)+6×(γ)1/2+0.5×(μ)≤62
• are satisfied,
• the length of the long side of γ phase is 30 μm or less,
• the length of the long side of μ phase is 15 μm or less, and
• κ phase is present in α phase.

A free-cutting copper alloy worked material that is obtained by performing any one or both of cold working and hot working, the free-cutting copper alloy worked material comprising:

• 75.0 mass % to 78.5 mass % of Cu;
• 2.95 mass % to 3.55 mass % of Si;
• 0.07 mass % to 0.28 mass % of Sn;
• 0.06 mass % to 0.14 mass % of P;
• 0.022 mass % to 0.25 mass % of Pb;
• and
• a balance including Zn and inevitable impurities,
• wherein a total amount of Fe, Mn, Co, and Cr as the inevitable impurities is lower than 0.08 mass %,
• when a Cu content is represented by [Cu] mass %, a Si content is represented by [Si] mass %, a Sn content is represented by [Sn] mass %, a P content is represented by [P] mass %, and a Pb content is represented by [Pb] mass %, the relations of
• 76.2≤f1=[Cu]+0.8×[Si]−8.5×[Sn]+[P]+0.5×[Pb]≤80.3 and
• 61.5≤f2=[Cu]−4.3×[Si]−0.7×[Sn]−[P]+0.5×[Pb]≤63.3
• are satisfied,
• in constituent phases of metallographic structure, when an area ratio of α phase is represented by (α) %, an area ratio of β phase is represented by (β) %, an area ratio of γ phase is represented by (γ) %, an area ratio of κ phase is represented by (κ) %, and an area ratio of μ phase is represented by (μ) %, the relations of
• 25≤(κ)≤65,
• 0≤(γ)≤1.5,
• 0≤(β)≤0.2,
• 0≤(μ)≤2.0,
• 97.0≤f3=(α)+(κ),
• 99.4≤f4=(α)+(κ)+(γ)+(μ),
• 0≤f5=(γ)+(μ)≤2.5,and
• 27≤f6=(κ)+6×(γ)1/2+0.5×(μ)≤70
• are satisfied,
• the length of the long side of γ phase is 30 μm or less,
• the length of the long side of μ phase is 25 μm or less, and
• κ phase is present in α phase;
• wherein an amount of Sn in κ phase is 0.08 mass % to 0.45 mass %, and
• an amount of P in κ phase is 0.07 mass % to 0.24 mass %.

A free-cutting copper alloy worked material that is obtained by performing any one or both of cold working and hot working, the free cutting copper alloy worked material comprising:

• 75.0 mass % to 78.5 mass % of Cu;
• 2.95 mass % to 3.55 mass % of Si;
• 0.07 mass % to 0.28 mass % of Sn;
• 0.06 mass % to 0.14 mass % of P;
• 0.022 mass % to 0.25 mass % of Pb;
• and
• a balance including Zn and inevitable impurities,
• wherein a total amount of Fe, Mn, Co, and Cr as the inevitable impurities is lower than 0.08 mass %,
• when a Cu content is represented by [Cu] mass %, a Si content is represented b [Si] mass %, a Sn content is represented by [Sn] mass %, a P content is represented by [P] mass %, and a Pb content is represented by [Pb] mass %, the relations of
• 76.2≤f1=[Cu]+0.8×[Si]−8.5×[Sn]+[P]+0.5×[Pb]≤80.3 and
• 61.5≤f2=[Cu]−4.3×[Si]−0.7×[Sn]−[P]+0.5×[Pb]≤63.3
• are satisfied,
• in constituent phases of metallographic structure, when an area ratio of α phase is represented by (α) %, an area ratio of β phase is represented by (β) %, an area ratio of γ phase is represented by (γ) %, an area ratio of κ is represented by (κ) %, and an area ratio of μ phase is represented by (μ) % the relations of
• 25≤(κ)≤65,
• 0≤(γ)≤1.5,
• 0≤(β)≤0.2,
• 0≤(μ)≤2.0,
• 97.0≤f3=(α)+(κ),
• 99.4≤f4=(α)+(κ)+(γ)+(μ),
• 0≤f5=(γ)+(μ)≤2.5,and
• 27≤f6=(κ)+6×(γ)1/2+0.5×(μ)≤70
• are satisfied,
• the length of the long side of γ phase is 30 μm or less,
• the length of the long side of μ phase is 25 μm or less, and
• κ phase is present in α phase;
• wherein a Charpy impact test value is higher than 14 J/cm2 and lower than 50 J/cm2,
• a tensile strength is 530 N/mm2 or higher, and
• a creep strain after holding the material at 150° C. for 100 hours in a state where a load corresponding to 0.2% proof stress at room temperature is applied is 0.4% or lower.

A free-cutting copper alloy worked material that is obtained by performing any one or both of cold working and hot working, the free-cutting copper alloy worked material comprising:

• 75.0 mass % to 78.5 mass % of Cu;
• 2.95 mass % to 3.55 mass % of Si;
• 0.07 mass % to 0.28 mass % of Sn;
• 0.06 mass % to 0.14 mass % of P;
• 0.022 mass % to 0.25 mass % of Pb;
• one or more elements(s) selected from the group consisting of 0.02 mass % to 0.08mass % of Sb, 0.02 mass % to 0.08 mass % of As, and 0.02 mass % to 0.30 mass % of Bi, and
• a balance including Zn and inevitable impurities,
• wherein a total amount of Fe, Mn, Co, and Cr as the inevitable impurities is lower than 0.08 mass %,
• when a Cu content is represented by [Cu] mass %, a Si content is represented by [Si] mass %, a Sn content is represented by [Sn] mass %, a P content is represented by [P] mass %, and a Pb content is represented by [Pb] mass %, the relations of
• 76.2≤f1=[Cu]+0.8×[Si]−8.5×[Sn]+[P]+0.5[Pb]≤80.3 and
• 61.5≤f2=[Cu]−4.3×[Si]−0.7×[Sn]−[P]+0.5×[Pb]≤63.3
• are satisfied,
• in constituent phases of metallographic structure, when an area ratio of α phase is represented by (α) %, an area ratio of β phase is represented by (β) %, an area ratio of γ phase is represented by (γ) %, an area ratio of κ phase is represented by (κ) %, and an area ratio of μ phase is represented by (μ) %, the relations of
• 25≤(κ)≤65,
• 0≤(γ)≤1.5
• 0≤(β)≤0.2,
• 0≤(μ)≤2.0,
• 97.0≤f3=(α)+(κ),
• 99.4≤f4=(α)+(κ)+(γ)+(μ),
• 0≤f5=(γ)+(μ)≤2.5, and
• 27≤f6=(κ)+6×(γ)1/2+0.5×(μ)≤70
• are satisfied,
• the length of the long side of γ phase is 30 μm or less,
• the length of the long side of μ phase is 25 μm or less, and
• κ phase is present of α phase;
• wherein an amount of Sn in κ phase is 0.08 mass % to 0.45 mass %, and
• an amount of P in κ phase is 0.07 mass % to 0.24 mass %.

A free-cutting copper alloy worked material that is obtained by performing any one or both of cold working and hot working, the free-cutting copper alloy worked material comprising:

• 75.0 mass % to 78.5 mass % of Cu;
• 2.95 mass % to 3.55 mass % of Si,
• 0.07 mass % to 0.28 mass % of Sn;
• 0.06 mass % to 0.14 mass % of P;
• 0.022 mass % to 0.25 mass % of Pb;
• one or more element(s) selected from the group consisting of 0.02 mass % to 0.08 mass % of Sb, 0.02 mass % to 0.08 mass % of As, and 0.02 mass % to 0.30 mass % of Bi;
• and
• a balance including Zn and inevitable impurities,
• wherein a total amount of Fe, Mn, Co, and Cr as the inevitable impurities is lower than 0.08 mass %,
• when a Cu content is represented by [Cu] mass %, a Si content is represented by [Si] mass %, a Sn content is represented by [Sn] mass %, a P content is represented by [P] mass %, and a Pb content is represented by [Pb] mass %, the relations of
• 76.2≤f1=[Cu]+0.8×[Si]−8.5×[Sn]+[P]+0.5×[Pb]≤80.3 and
• 61.5≤f2=[Cu]−4.3×[Si]−0.7×[Sn]−[P]+0.5×[Pb]≤63.3
• are satisfied,
• in constituent phases of metallographic structure, when an area ratio of α phase is represented by (α) %, an area ratio of β phase is represented by (β) %, an area ratio of γ phase is represented by (γ) %, an area ratio of κ phase is represented by (κ) %, and an area ratio of μ phase is represented by (μ) %, the relations of
• 25≤(κ)≤65,
• 0≤(γ)≤1.5,
• 0≤(β)≤0.2,
• 0≤(μ)≤2.0,
• 97.0≤f3=(α)+(κ),
• 99.4≤f4=(α)+(κ)+(γ)+(μ),
• 0≤f5=(γ)+(μ)≤2.5, and
• 27≤f6=(κ)+6×(γ)1/2+0.5×(μ)≤70
• are satisfied,
• the length of the long side of γ phase is 30 μm or less,
• the length of the long side of μ phase is 25 μm or less, and
• κ phase is present in α phase;
• and
• wherein a Charpy impact test value is higher than 14 J/cm2 and lower than 50 J/cm2,
• a tensile strength is 530 N/mm2 or higher, and
• a creep strain after holding the material at 150° C. for 100 hours in a state where a load corresponding to 0.2% proof stress at room temperature is applied is 0.4% or lower.